Field of the Invention
The invention relates to a method and an apparatus for controlling an internal combustion engine which is associated with a sensor that senses a measured variable from which an estimated value of a torque loss of the internal combustion engine is derived, in which a measured value of the measured variable is determined at prescribed time intervals in each case.
German Published, Non-Prosecuted Patent Application DE 43 04 779 A1 discloses a method and an apparatus for controlling an internal combustion engine. An estimated value of the torque loss is determined through the use of a characteristic diagram from an engine speed and engine temperature, while taking a torque requirement of secondary assemblies such as an air conditioning unit, a generator or a power steering system, into account. Furthermore, the estimated value of the torque loss is adapted through the use of a steady-state deviation of a correction moment contribution of an idling speed regulator. A driver's requested torque is calculated as a function of an accelerator pedal position of an accelerator pedal and an indexed torque is determined therefrom as a function of the estimated value of the torque loss. The indexed torque is then set by prescribing corresponding setpoint values for actuators which influence the torque. The known document does not propose which measures are to be performed for a reliable operation of the internal combustion engine.
Published German Patent Application DE 39 90 872 T1, corresponding to International Publication WO 90/01631, discloses a further method and apparatus for controlling an internal combustion engine. If a failure of a temperature sensor for a cooling water temperature is detected, the control of the internal combustion engine is carried out by assuming a permanently prescribed water temperature (for example 80.degree. C.).